Targeted lessons
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Year 13
Side B5: Astronomy
Finish Side B with stars, distance measurements, and redshift.
Part of Year 13 CIE Physics 9702.
Topic Overview
What students will cover
This topic closes Year 13 with large-scale astrophysics ideas. You should be able to use observed radiation to infer properties that cannot be measured directly, including stellar luminosity, temperature, radius, distance, and galaxy recession speed.
The lesson sequence moves from standard candles and inverse-square reasoning into redshift and Hubble’s law. Keep the evidence chain clear: observations become measurements, measurements support models, and those models explain why an expanding universe is the best interpretation of the data.
Revision
Topic revision route
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Recall vocabulary
luminosity
A definition has not been added for this term yet. Use the lesson sequence below to review where it appears.
radiant flux
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standard candle
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inverse square law
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Wien's displacement law
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Stefan-Boltzmann law
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redshift
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Hubble's law
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surface temperature
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stellar radius
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recessional velocity
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expanding universe
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Resource bank
- Lesson resources
- 7
- Topic resources
- 1
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Syllabus CIE 9702 coverage in this topic
11 points across 3 lessons
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CIE 9702 coverage in this topic
11 points across 3 lessons
25.1.1
understand the term luminosity as the total power of radiation emitted by a star
25.1.2
recall and use the inverse square law for radiant flux intensity F in terms of the luminosity L of the source F = L / (4πd 2)
25.1.3
understand that an object of known luminosity is called a standard candle
25.1.4
understand the use of standard candles to determine distances to galaxies
25.2.1
recall and use Wien’s displacement law λmax ∝ 1 / T to estimate the peak surface temperature of a star
25.2.2
use the Stefan–Boltzmann law L = 4πσr 2 T 4
25.2.3
use Wien’s displacement law and the Stefan–Boltzmann law to estimate the radius of a star
25.3.1
understand that the lines in the emission and absorption spectra from distant objects show an increase in wavelength from their known values
25.3.2
use ∆λ / λ . ∆f / f . v / c for the redshift of electromagnetic radiation from a source moving relative to an observer
25.3.3
explain why redshift leads to the idea that the universe is expanding
25.3.4
recall and use Hubble’s law v . H0 d and explain how this leads to the Big Bang theory (candidates will only be required to use SI units) Faculty feedback: ‘Understanding how and why our climate is changing and providing the knowledge and skills to explore the challenges plays a key role in every student’s education.’ Feedback from: Dr Amy Munro-Faure, Head of Education and Student Engagement of Cambridge Zero
Lessons
Lesson sequence
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Lesson
01Standard Candles
Introduce standard candles, luminosity and radiant flux.
Lesson
02Standard Candles and Calculating Distances
Use standard candles to estimate astronomical distances.
Lesson
03Redshift and Hubble's Law
Use redshift evidence and Hubble's law to describe the expanding universe.
Shared Materials
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